The ongoing research program for which continued support is being requested is directed at a quantitative delineation of mechanisms underlying the visual perception of direction. This work is being carried out mainly - although not solely - through experiments in which measurements of eye movements (contact lens technique) and psychophysical reports of visual direction are simultaneously obtained. These simultaneous measurements permit us to establish separately the roles played by the spatio-temporal patterm of light on the retina and by extraretinal processes in a variety of psychophysical situations. Five related main lines of work are proposed. These are outlined under the separate headings: (1) Visual Perception of Direction When Voluntary Saccades Occur; (2) Visual Perception of Direction and Vernier Acuity as Related to Involuntary Eye Movements; (3) Visual Direction -Four Classes of Interesting Phenomena; (4) Visual Direction, Visual Orientation, and Visual Persistence; (5) Visual Direction and Pursuit Eye Movements. The four classes of phenomena in (3) are: (a) Binocular Flash Diplopia, (b) Autokinesis, (c) Tilt Adaptation and Movement Adaptation, and (d) Binocular Depth Contrast. BIBLIOGRAPHIC REFERENCES: Cantor, B.I., Matin, L., and Teich, M.C. Dead-Time-Corrected Photocounting Distributions With Arbitrary Dead Time. Applied Optics, Dec.,1975. In press. Boff, K., Matin, L., and Pola, J. An Illusion of Vernier Offset Produced by Rotary Target Motion. Presented at spring meeting of East. Psych. Assoc., 1975, New York.